1. Field of the Invention
The present invention relates to an image processing apparatus that processes original document data acquired by optically scanning an original document.
2. Description of the Related Art
Recently, with the aim of saving space, a network multifunction peripheral has been widely used that combines copying, network scanner and network printer functions into one unit.
Such network multifunction peripherals include a scanner device. By transferring image data acquired by optically scanning an original document using the scanner device to a built-in printer device, and to terminal and printer devices that are connected through a network, the copying, network scanner and network printer functions are achieved.
In the network multifunction peripheral, it is preferable to properly perform adjustment (hereinafter, referred to as color calibration) for accurately reproducing colors (including hue and black-and-white tone) of the original document on a copy of the original document.
Color calibration is generally performed by using a standard image (referred to as a calibration chart) in which a plurality of standard colors are present. For example, specialists make a copy of the calibration chart using a machine on which color calibration is to be performed, and perform the color calibration by comparing the original and the copy thereof with the naked eye.
A technique is also well known by which color calibration can be easily and properly performed by a general user without requiring the user to compare the original and the copy thereof with the naked eye.
A conventional image forming apparatus includes a control unit that performs a color correcting operation that compares scanned data acquired by scanning with a scanner unit a standard image including a standard tone or color bar, and scanned data acquired by scanning with the scanner unit a comparison image acquired by having the former scanned data printed by a printer unit, and that determines a correction value that brings the tone or hue of the scanned data of the comparison image close to the tone or hue of the scanned data of the standard image.
With the above configuration, since the correction value is determined by the image forming apparatus, it is not necessary to compare the colors with the naked eye, and even a general user can easily and properly perform color calibration.
In color calibration, it is generally important to use a proper standard image (hereinafter, referred to as a calibration chart). For example, if a calibration chart deteriorated with time is used, accurate color calibration cannot be performed.
subtle changes in color on the calibration chart cannot be perceived with the naked eye. Whether or not the calibration chart is usable can be determined by using a measuring instrument. However, such measuring instruments are expensive and generally used by specialists.
Accordingly, there is a problem in that as color calibration becomes easy for a general user to perform using conventional techniques, there is still no method by which the general user can easily know appropriateness of the calibration chart.